Infertility affects 10-15% of couples in the United States and Polycystic Ovarian Syndrome (PCOS) is a common endocrine disorder that contributes to infertility in women. The most widely accepted clinical definition of PCOS is the association of hyperandrogenism with chronic anovulation in women without specific underlying disease of the adrenal or pituitary gland. Over the years, animal models of polycystic ovaries (PCO) have been utilized in studies designed to facilitate the development of effective clinical interventions for this condition. In this study, we will utilize an experimental dehydroepiandrosterone (DHEA)-induced PCO rat model to elucidate fundamental molecular mechanisms of cystogenesis. It is hypothesized that hyperandrogenism induces molecular and genetic changes that affect follicular development that may contribute to ovarian cyst formation. Studies designed will employ differential mRNA display and other conventional molecular approaches to: 1) identify cellular gene products associated with DHEA-induced cystogenesis; 2) isolate and characterize genes involved in ovarian cyst formation; 3) determine the contribution of DHEA targeted proteins in the ovarian cystogenic process. The goal of this proposal is to identify and characterize hormonally induced early gene expression during ovarian cyst formation. Results from this study will contribute new knowledge that will facilitate a better understanding of ovarian function as well as the role of hormonal mechanisms in cyst development.